The subject matter disclosed herein relates to turbines. Specifically, the subject matter disclosed herein relates to seals in gas turbines.
The main gas-flow path in a gas turbine commonly includes the operational components of a compressor inlet, a compressor, a turbine and a gas outflow. There are also secondary flows that are used to cool the various heated components of the turbine. Mixing of these flows and gas leakage in general, from or into the gas-flow path, is detrimental to turbine performance.
The operational components of a gas turbine are contained in a casing. The turbine is commonly surrounded annularly by adjacent arc segments. As used herein, the term “arcuate” may refer to a member, component, part, etc. having a curved or partially curved shape. The adjacent arc segments include outer shrouds, inner shrouds, nozzle blocks, and diaphragms. Arc segments may provide a container for the gas-flow path in addition to the casing alone. Arc segments may secure other components of the turbine and may define spaces within the turbine. Between each adjacent pair of arc segments is a space that permits the arc segments to expand as the operation of the gas turbine forces the arc segments to expand.
Slots are defined on the sides of each arc segment for receiving a seal in cooperation with an adjacent slot of an adjacent arc segment. The seal is placed in the slot to prevent leakage between the areas of the turbine on either side of the seal. These areas may include the main gas-flow path and secondary cooling flows.
The slots within the end of a particular arc segment may be angled in orientation to each other and the slots may connect. When a planar seal is received in each of the two slots that are connected, a gap is left between the two seals. This gap permits leakage between the internal and external areas of the gas turbine. Reducing this gap improves gas turbine performance.